Radar Measurement Technology - DLR Portal · conditions and time of day, radar mea-surement technology is also used in aviation. The screens in air traffic control centers constantly

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Radar Measurement TechnologyUsing microwaves

Ever since the young scientist Heinrich Hertz first supplied the evidence in 1886 that electromagnetic waves are reflected by metallic objects, methods involving microwaves have been num-bered among the most important measurement technologies ever developed.

We now look back on over 100 years of radar technology. The developments that have taken place since 1904 (C. Hülsmeyer’s “telemobiloscope”) progressed at an enormous pace. The DLR_School_Lab radar experiment illustrates the basic principles and provides an introduction to radar technology.

Aerospace and shipping, but also land surface traffic, would hardly be possible without the accurate measurements provided by radar systems. The precise measurement and mapping of planet Earth is also based to a large extent on radar data.

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Radar Measurement Technology

The Radar Principle

RadarRadar has significant advantages compared with optical and acoustic measurement methods. The reason is the me thodology: radar actively emits microwaves. On their path these waves encounter objects which reflect them back. Also called the “echo,” these re-turning waves are systematically analyzed at their place of reception. Because it emits microwaves, radar can function independently of weather conditions and the time of day to supply reliable data.

Applications for Radar Measurement Technology

TerraSAR-XAt DLR radar is used in a wide variety of fields. It is especially common in avia-tion and aerospace. One example is the TerraSAR-X mission, a joint undertaking of DLR and the space company Astrium. This radar satellite provides images of the earth’s surface with a spatial resolu-tion down to one meter; a performance

Fig. 1: The German radar satellite TerraSAR-X

now available for the first time to civilian users. Other radar satellites are in the planning stage.

AviationBecause of its independence of weather conditions and time of day, radar mea-sure ment technology is also used in aviation. The screens in air traffic control centers constantly reveal the location of aircraft, as well as their velocity and alti-tude. Radar is also used at DLR for flight monitoring.

Road trafficRadar measurement technology is also routinely used to measure road traffic velocities.

MeteorologyAnother application field is meteorology, where radar is used for early identifica-tion and location of storm fronts in order to increase the quality of weather forecasts.

Fig. 2: TerraSAR-X radar image of the pyramids of Giza

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Radar Measurement Technology at DLR_School_Lab Oberpfaffenhofen

The Experiment

The focus of the radar measurement technology experiment is on conveying the principle behind radar range and velocity measurements. The experiment is for those students for whom practical as-pects of wave propagation may not have been dealt with in physics classes.

At the end of the experiment the students will know how to detect and locate objects using microwaves, how to determine their velocity and direction of movement, and even how the total air traffic situation can be monitored.

For this purpose there is a complete system for measuring distance and velo-city available at the DLR_School_Lab. The students can gain experience in radar measurement technology at two experi-ment set-ups equipped with various radar sensors. The possibilities and limitations are revealed, and by making connec-

tions to daily life their understanding of technical measurement proce dures is deepened.

Glossary

RadarRadar is a detection method involving the emission of electromagnetic waves, their reflection by some object and their sub-sequent recapture. This sequence allows deductions to be made about the velocity and location of the object.

SARSAR is an abbreviation for Synthetic Aperture Radar. It is demonstrated using the E-SAR system on board a DLR research airplane, the Dornier DO-228. This imaging radar sensor uses five dif-ferent frequency ranges so that wave-lengths between 3 cm and 100 cm can be covered.

MicrowavesMicrowaves are electromagnetic waves whose wavelengths range from 1 mm to 1 m.

Fig. 3: The DO-228 research aircraft with an E-SAR radar system

Fig. 4: Students at DLR_School_Lab

List of Figures

Cover image: The separate steps from a radar image to a digital terrain map, shown on a data set from the Shuttle Radar Topography Mission (SRTM)German Aerospace Center DLR

Fig. 1: The German radar satellite TerraSAR-X German Aerospace Center DLR

Fig. 2: TerraSAR-X radar image of the pyramids of GizaGerman Aerospace Center DLR

Fig. 3: The DO-228 research aircraft with an E-SAR radar systemGerman Aerospace Center DLR

Fig. 4: Students at DLR_School_LabGerman Aerospace Center DLR

DLR at a Glance

DLR is Germany’s national aeronautics and space research center. Its extensive research and development activities in the fields of aeronautics, space, trans-portation and energy are integrated in national and international cooperative ventures. In addition to this research, as Germany’s space agency the federal government has given DLR the responsi-bility to plan and implement the German space program and to represent German interests internationally. DLR is also the umbrella organization for Germany’s larg-est project management agencies.

Approximately 6,500 people are employed at DLR’s 13 locations, which include Köln (headquarters), Berlin, Bonn, Braunschweig, Bremen, Göttingen, Hamburg, Lampoldshausen, Neustrelitz, Oberpfaffenhofen, Stuttgart, Trauen and Weilheim. DLR also operates offices in Brussels, Paris and Washington D.C.

DLR Oberpfaffenhofen

Aerospace, environment and transporta-tion are DLR’s primary fields of interest in Oberpfaffenhofen. Some 1,500 people work there in nine different institutes and facilities, making DLR Oberpfaffenhofen the largest DLR location.

DLR_School_Lab OberpfaffenhofenMünchner Straße 2082234 Weßling

Contacts:Head: Dr. Dieter HausamannTelephone +49 8153 28-2770Telefax +49 8153 28-1070E-Mail [email protected]

School_Lab team assistant: Stefani KrznaricTelephone +49 8153 28-1071Telefax +49 8153 28-1070E-Mail [email protected]

www.DLR.de/dlrschoollab